title: Strategic design of an effective beta-lactamase inhibitor: LN-1-255, a 6-alkylidene-2'-substituted penicillin sulfone.
abstract: In an effort to devise strategies for overcoming bacterial beta-lactamases, we studied LN-1-255, a 6-alkylidene-2'-substituted penicillin sulfone inhibitor. By possessing a catecholic functionality that resembles a natural bacterial siderophore, LN-1-255 is unique among beta-lactamase inhibitors. LN-1-255 combined with piperacillin was more potent against Escherichia coli DH10B strains bearing bla(SHV) extended-spectrum and inhibitor-resistant beta-lactamases than an equivalent amount of tazobactam and piperacillin. In addition, LN-1-255 significantly enhanced the activity of ceftazidime and cefpirome against extended-spectrum cephalosporin and Sme-1 containing carbapenem-resistant clinical strains. LN-1-255 inhibited SHV-1 and SHV-2 beta-lactamases with nm affinity (K(I) = 110 +/- 10 and 100 +/- 10 nm, respectively). When LN-1-255 inactivated SHV beta-lactamases, a single intermediate was detected by mass spectrometry. The crystal structure of LN-1-255 in complex with SHV-1 was determined at 1.55A resolution. Interestingly, this novel inhibitor forms a bicyclic aromatic intermediate with its carbonyl oxygen pointing out of the oxyanion hole and forming hydrogen bonds with Lys-234 and Ser-130 in the active site. Electron density for the "tail" of LN-1-255 is less ordered and modeled in two conformations. Both conformations have the LN-1-255 carboxyl group interacting with Arg-244, yet the remaining tails of the two conformations diverge. The observed presence of the bicyclic aromatic intermediate with its carbonyl oxygen positioned outside of the oxyanion hole provides a rationale for the stability of this inhibitory intermediate. The 2'-substituted penicillin sulfone, LN-1-255, is proving to be an important lead compound for novel beta-lactamase inhibitor design.
authors.affiliation: Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA.
authors.forename: Priyaranjan
authors.initials: P
authors.lastname: Pattanaik
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Bethel
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Hujer
authors.forename: Kristine M
authors.initials: KM
authors.lastname: Hujer
authors.forename: Anne M
authors.initials: AM
authors.lastname: Distler
authors.forename: Magdalena
authors.initials: M
authors.lastname: Taracila
authors.forename: Vernon E
authors.initials: VE
authors.lastname: Anderson
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Fritsche
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
authors.forename: Sundar Ram Reddy
authors.initials: SR
authors.lastname: Pagadala
authors.forename: Focco
authors.initials: F
authors.lastname: van den Akker
authors.forename: John D
authors.initials: JD
authors.lastname: Buynak
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bonomo
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D020134:Catalytic Domain; D003499:Cyclic S-Oxides / Q000737:chemistry* / Q000494:pharmacology*; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D007700:Kinetics; D050296:Microbial Viability / Q000187:drug effects; D010406:Penicillins / Q000737:chemistry / Q000494:pharmacology*; D021241:Spectrometry, Mass, Electrospray Ionization; D013450:Sulfones / Q000737:chemistry*; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D003499:Cyclic S-Oxides; D004791:Enzyme Inhibitors; C538899:LN 1-255; D010406:Penicillins; D013450:Sulfones; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases